Sir Stuart Rose, the chief executive of Marks & Spencer, has called upon Jeremy Paxman to put his pants on the line and settle a debate that is threatening to divide the nation.

Sir Stuart has invited the presenter of the BBC’s Newsnight programme to have his pants tested by M&S’s technical specialists to see if his claim of a decline in quality bears up to examination.

The Times has also been invited along to watch. Sir Stuart said: “I’m inviting him in to see our specialists. My message to Jeremy is: bring them in — we will put them to the test. We’ll sort your tackle out.”

The comments came as Sir Stuart mounted a passionate defence of M&S underwear after the huge media coverage given to Paxman’s complaint, sent by e-mail and leaked at the weekend.

Paxman said there was “widespread anxiety” at the lack of support in M&S pants and that its socks were wearing out too quickly.

Paxman said he would be delighted to accept the challenge. He said: “Nothing I have ever done — interviewing Michael Howard, asking Tony Blair whether he prays with George Bush, nothing — has elicited such a response. I have been deluged with e-mails; strangers have accosted me in the street saying, ‘Good on you’. There is a real issue here.

“I wrote to Sir Stuart because I think Marks & Spencer is an iconic British brand and I want them to do well. They will not do well in this field with this level of quality.”

Sir Stuart said the complaint was in stark contrast to the overwhelming satisfaction felt by millions of other M&S customers. M&S sells 32 million pairs of underpants and 44 million pairs of socks each year.

He told The Times: “Our returns on pants are just 0.08 per cent, and socks 0.06 per cent. People return anything they’re not happy with. If we had a problem our returns would be over 1 per cent, but they’re not even over 0.1 per cent. I wear M&S underpants and I’m not rolling around.”

He added: “Jeremy wasn’t very precise — it was just a general complaint that they were not as comfortable as they used to be. As people get older they tend to need a bit more support. Perhaps that’s the problem.”

Marks & Spencer sells one in every five pairs of Y-fronts and boxer shorts sold on the high street.

Sir Stuart said that despite fierce competition from the likes of Tesco and Primark, the company’s strictness on quality had not changed. M&S buyers specify the length of yarn used, the strength and the smoothness — all critical to the garment holding its colour and not shrinking.

“If you get ten pairs of white underpants from different retailers, including ourselves, wash them ten times, hang them out to dry, some would be grey, some would have shrunk and ours would be pretty passable.

“We are the only retailer to have a team of 70 people dedicated to rigorous testing, of yarn, the fit and shrinkage. Our shrinkage is the lowest you can get.

“When you go to a supermarket I can understand the temptation to throw in some pants and socks but if you did you’d be going back for more pretty quickly. You’re better off choosing more quality in the first place.”

He added that Paxman was not being given special treatment. “We take all our customers seriously. I get letters all the time, half of which are positive, half of which are negative. I respond to all of them.”

The debate has already dragged in the store chain’s rivals. Asda, home of the George clothing brand, said it was sending Paxman a selection of its Y-fronts and boxer shorts. A spokesman said: “We’ve been panting to enter this debate.”